Field of the Invention
This invention relates generally to fluid circuit components useful in the operation of valves, more particularly to fluid circuit components useful in the operation of valves for operation of offshore and subsea blow out preventer (BOP) control systems.
Background of the Invention
In recent years, the subsea and onshore drilling industries have required increased BOP control system operating pressures and flow rates in order to meet new requirements for BOP closing times. To meet faster RAM type and annular type BOP closing times, higher hydraulic fluid velocities and stored system energy levels (i.e., higher pressure operation) than those used previously are required. Because of this, there is a need for new types of hydraulic valve systems for offshore and subsea BOP control systems that are capable of handling higher hydraulic fluid velocities and system energy levels.
Rigorous maintenance, testing, and functional requirements specified by new industry regulations place additional demands on control systems and associated piping and fluid conduits. Functional testing is done to ensure the operational integrity of the hydraulic circuits and control circuits used to operate the BOP, and of the BOP itself, and thus verify that the BOP is still capable of operating within the required closing time span in the event the need to do so arises. Functional testing of, as well as actual operation of, the fluid circuits, control circuits and BOP can create pressure spikes in the fluid control circuitry great enough to damage equipment, valves, and connected piping. These pressure spikes may be created when hydraulic control valves are rapidly opened or closed in high pressure hydraulic systems with extremely high flow rates. In order to mitigate the potential damage from pressure spikes occurring during both testing and drilling, there is a present need for a mechanism to remove or ameliorate the severity of these pressure spikes, and thus maintain the integrity of the BOP control system.